Nerve stimulation can be applied in the treatment of a range of conditions. The nerve stimulation may be applied to control muscle activity or to generate sensory signals. Nerves may be stimulated by surgically implanting electrodes in, around or near the nerves and driving the electrodes from an implanted or external source of electricity.
The phrenic nerve normally causes the contractions of the diaphragm that are necessary for breathing. Various conditions can prevent appropriate signals from being delivered to the phrenic nerve. These include:    chronic or acute injury to the spinal cord or brain stem;    Amyotrophic Lateral Sclerosis (ALS);    disease affecting the spinal cord or brain stem; and, decreased day or night ventilatory drive (e.g. central sleep apnea, Ondine's curse).These conditions affect significant numbers of people.
Mechanical ventilation may be used to help patients breathe. Some patients require chronic mechanical ventilation. Mechanical ventilation can be lifesaving but has a range of significant problems. Mechanical ventilation:    tends to provide insufficient venting of the lungs. This can lead to accumulation of fluid in the lungs and susceptibility to infection.    requires apparatus that is not readily portable. A patient on ventilation is tied to a ventilator. This can lead to atrophy of muscles (including breathing muscles) and an overall decline in well being.    can adversely affect venous return because the lungs are pressurized.    interferes with eating and speaking.    requires costly maintenance and disposables.
Phrenic nerve pacing uses electrodes implanted in the chest to directly stimulate the phrenic nerve. The Mark IV Breathing Pacemaker System available from Avery Biomedical Devices, Inc. of Commack, N.Y. USA is a diaphragmatic or phrenic nerve stimulator that consists of surgically implanted receivers and electrodes mated to an external transmitter by antennas worn over the implanted receivers. Implanting electrodes and other implantable components for phrenic nerve pacing requires significant surgery. The surgery is complicated by the fact that the phrenic nerve is small (approx. diameter 2 mm) and delicate. The surgery involves significant cost.
Laproscopic diaphragm pacing being developed by Case Western Reserve University bio-medical engineers and physician researchers is another technique for controlling breathing. Devices for use in Laproscopic diaphragm pacing are being developed by Synapse Biomedical, Inc. Laproscopic diaphragm pacing involves placing electrodes at motor points of the diaphragm. A laparoscope and a specially designed mapping procedure are used to locate the motor points.
References that in the field of nerve stimulation include:    Moffitt et al., WO 06/110338A1, entitled: TRANSVASCULAR NEURAL STIMULATION DEVICE;    Caparso et al., US 2006/0259107, entitled: SYSTEM FOR SELECTIVE ACTIVATION OF A NERVE TRUNK USING A TRANSVASCULAR RESHAPING LEAD;    Dahl et al., WO 94/07564 entitled: STENT-TYPE DEFIBRILLATION ELECTRODE STRUCTURES;    Scherlag et al., WO 99/65561 entitled: METHOD AND APPARATUS FOR TRANSVASCULAR TREATMENT OF TACHYCARDIA AND FIBRILLATION;    Bulkes et al., US20070288076A1 entitled: BIOLOGICAL TISSUE STIMULATOR WITH FLEXIBLE ELECTRODE CARRIER;    Weinberg et al., EP 1304135 A2 entitled: IMPLANTABLE LEAD AND METHOD FOR STIMULATING THE VAGUS NERVE;    Moffitt et al., US20060259107 entitled: SYSTEM FOR SELECTIVE ACTIVATION OF A NERVE TRUNK USING A TRANSVASCULAR RESHAPING LEAD;    Denker et al. U.S. Pat. No. 6,907,285 entitled: IMPLANTABLE DEFIBRILLATOR WITH WIRELESS VASCULAR STENT ELECTRODES;    Chavan et al. US20070093875 entitled IMPLANTABLE AND RECHARGEABLE NEURAL STIMULATOR;    Rezai, U.S. Pat. No. 6,885,888 entitled ELECTRICAL STIMULATION OF THE SYMPATHETIC NERVE CHAIN;    Mehra, U.S. Pat. No. 5,170,802 entitled IMPLANTABLE ELECTRODE FOR LOCATION WITHIN A BLOOD VESSEL;    Mahchek et al. U.S. Pat. No. 5,954,761 entitled: IMPLANTABLE ENDOCARDIAL LEAD ASSEMBLY HAVING A STENT;    Webster Jr. et al. U.S. Pat. No. 6,292,695 entitled: METHOD AND APPARATUS FOR TRANSVASCULAR TREATMENT OF TACHYCARDIA AND FIBRILLATION;    Stokes, U.S. Pat. No. 4,643,201;    Ela Medical SA, EP 0993840A, U.S. Pat. No. 6,385,492    WO 9407564 describes stent-type electrodes that can be inserted through a patient's vasculature.    WO 9964105A1 describes transvascular treatment of tachycarida.    WO 9965561 A1 describes a method and apparatus for transvascular treatment of tachycardia and fibrillation.    WO02058785A1 entitled VASCULAR SLEEVE FOR INTRAVASCULAR NERVE STIMULATION AND LIQUID INFUSION describes a sleeve that includes an electrode for stimulating nerves.    WO 06115877A1 describes vagal nerve stimulation using vascular implanted devices.    WO 07053508A1 entitled INTRAVASCULAR ELECTRONICS CARRIER AND ELECTRODE FOR A TRANSVASCULAR TISSUE STIMULATION SYSTEM and US20070106357A1 describe an intravascular mesh type electrode carrier in which the conductor of a lead is interwoven into the carrier mesh.    U.S. Pat. No. 5,224,491 describes implantable electrodes for use in blood vessels.    U.S. Pat. No. 5,954,761 describes an implantable lead carrying a stent that can be inserted into the coronary sinus.    U.S. Pat. No. 6,006,134 describes transvenous stimulation of nerves during open heart surgery.    U.S. Pat. No. 6,136,021 describes an expandable electrode for coronary venous leads (the electrode can be placed or retained in the vasculature of the heart).    Spreigl et al. U.S. Pat. No. 6,161,029 entitled: APPARATUS AND METHOD FOR FIXING ELECTRODES IN A BLOOD VESSEL describes fixing electrodes in blood vessels.    U.S. Pat. No. 6,438,427 describes electrodes for insertion into the coronary sinus.    U.S. Pat. No. 6,584,362 describes leads for pacing and/or sensing the heart from within the coronary veins.    U.S. Pat. No. 6,778,854 describes use of electrodes in the Jugular vein for stimulation of the Vagus nerve.    U.S. Pat. No. 6,934,583 discloses stimulation of the Vagus nerve with an electrode in a blood vessel.    U.S. Pat. No. 7,072,720 describes catheter and tube electrode devices that incorporate expanding electrodes intended to contact the interior walls of blood vessels or anatomic structures in which the electrode devices are implanted as well as methods involving stimulation of the vagus nerve.    U.S. Pat. No. 7,184,829 discloses transvascular stimulation of a vagal nerve.    U.S. Pat. No. 7,225,019 discloses intravascular nerve stimulation electrodes that may be used in the Jugular vein.    U.S. Pat. No. 7,231,260 describes intravascular electrodes.    Schauerte et al., US 2002/0026228 entitled: ELECTRODE FOR INTRAVASCULAR STIMULATION, CARDIOVERSION AND/OR DEFIBRILLATION;    Jonkman et al., U.S. Pat. No. 6,006,134    Bonner et al., U.S. Pat. No. 6,201,994    Brownlee et al., U.S. Pat. No. 6,157,862    Scheiner et al., U.S. Pat. No. 6,584,362    Psukas, WO 01/00273    FR 2801509, US 2002065544    Morgan, U.S. Pat. No. 6,295,475    Bulkes et al., U.S. Pat. No. 6,445,953    Rasor et al. U.S. Pat. No. 3,835,864 entitled: INTRA-CARDIAC STIMULATOR    Denker et al. US20050187584    Denker et al. US20060074449A1 entitled: INTRAVASCULAR STIMULATION SYSTEM WITH WIRELESS POWER SUPPLY;    Denker et al. US20070106357A1 entitled: INTRAVASCULAR ELECTRONICS CARRIER ELECTRODE FOR A TRANSVASCULAR TISSUE STIMULATION SYSTEM;    Boveja et al. US20050143787    Transvenous Parassympathetic cardiac nerve stimulation; an approach for stable sinus race control, Journal of Cardiovascular Electrophysiology 10(11) pp. 1517-1524 November 1999    Transvenous Parassympathetic nerve stimulation in the inferior vena cava and atrioventricular conduction, Journal of Cardiovascular Electrophysiology 11(1) pp. 64-69, January 2000.    Planas et al., Diaphragmatic pressures: transvenous vs. direct phrenic nerve stimulation, J. Appl. Physiol. 59(1): 269-273, 1985.    Yelena Nabutovsky, M. S. et al., Lead Design and Initial Applications of a New Lead for Long-Term Endovascular Vagal Stimulation, PACE vol. 30, Supplement 1, January 2007 p. S215
Other references of interest include:    Amundson, U.S. Pat. No. 5,779,732
There remains a need for surgically simpler, cost-effective and practical apparatus and methods for nerve stimulation.